Internal-combustion engine



F. PQRSCHE INTERNAL CQMBUSTIOH ENGINE Filed Jan 14. 1925 Patented July13, 1926.- p

UNITED STATES PATENT OFFICE.

FERDINAND PORSCHE, 013 STUT'IGART-UNTERTURKHEIM, GERMANY. ASSIGNOR TODAIMLER-MOTOR-EN-GESELLSCHAFT. F WURTTEMBERG. GERMANY, A CORPO- RATIONOF GERMANY.

INTERNAL-COMBUSTION ENGINE.

Applications for this invention have been filed as follows: Germany,Sept. 28, 1923; Great Britain, Sept. 29, 1924:; France, Sept.

- 27, 1924:; Italy, Sept. 27, 1924;; Austria, Sept. 27, 1924. v

This invention relates to an improved internal combustion engineoperating by means of self ignition,

The reason why engines with self ignition cannot be employed is that theuse of self ignition involves an explosive ignition shock of the entirecharge so that considerable shocks are exerted on the pistons and theconstruct-ional parts connected therewith which cause what is commonlyknown as knocking which leads to the rapid destruction of the engine. 7

Apart from the question of knocking, assuming the knocking to beovercome, it is essential for the operation of an engine at low or highspeeds to provide means to prevent the ignition shock taking placebefore the dead point is reached.

In itself the normal ignition, that is to say the shock producingexplosion of the entire cylinder contents, is not connected with highspeeds but the carrying out of this normal ignition method is impossibleon account of the-said knocking. If therefore, it is desired to operatethe engine with, shock ignition by increasing the compressiontemperature sufficiently to cause self ignition knocking must first beprevented.

One object of the invention is to provide meansto prevent knocking.

A further object of the invention is to provide a high speed engineutilizing self ignition.

The method of operation of thisinvention consists in composing indifferent ways as regards its self ignition temperature the mixture offuel and air. which is to be brought to combustion by the heat ofcompression.

In order to form the mixture orexplosive compound two or morecombustibles are em ployed, the self ignition temperature of one ofwhich lies somewhat below the compression temperature produced by theworking piston, so that the part of the. mixture or of the explosivecompound formed from this fuel in the cylinder produces an explosion onignition, ature of the proceeds more rapidly whilst the self ignitiontemperother fuel lies above the com- 2,452, and in Germany September 28,1923.

pression temperature produced by the working piston so that noself'ignition of this part of the mixture can possibly take place.

By a suitable formation of the compression chamber or by suitableintroduction of the two elements of the mixture or compound, provisionis preferably made -to prevent any substantial mixture of these twoparts of the compound.

If a. differently constituted mixture or compound as set forth above becompressed, an explosion takes place in the more easily ignitable partbut the suddenly formed pressuredoes not act directly on the pistons toproduce the dreaded knocking, but the suddenly formed pressure firstcompresses the other part of the compound and ignites it so that thispart in turn is able to develop a pressure corresponding to itscombustion temperature.

The ignition of one part of the compound of course proceedsextremelyrapidly. But.

the development of the pressure of the sec- 0nd less inflammable part ofthe compound as compared with normal ignition by means of an electricspark, as the flame derived from the explosion of the more easilyignitable part of the compound has a larger active surface than thesparks of one or even more sparking plugs.

However, there is no explosion wherein the maximum explosion pressureinstantaneously results but this takes place as a somewhat reton and thecrank may reach the dead point in order that the highest pressure isdevel oped at the dead point. 1

The crank must therefore have a high angular velocity which in motorshaving .a limited stroke such as are employed onautomobiles issynonymous with high speed.

It is obvious that the compound may also be formed of more than twofuels.

One example of construction illustrating the method of operation isshown in the accompanying drawing.

The diagram shows forexamplea working cylinder (1 provided with an inletand outlet. valve, on said cylinder connects with a cylinder 1) ofsmaller'diameter which is also provided with an inlet and outlet valve.

In said smaller cylinder 6 is introduced that stricted developmentduring which the pis- I compression temperature; in said larger cyl:inder a is introduced that portion of the mixture, the ignitiontemperature of which is higher than the compression ten'iperature.

The ignition flame is conveyed through the ignition passage and in orderthat no mixture of the layers of the compound contained in the twoignition chambers may take place, both layers are compressed to auniform degree of compression. As both chambershave separate inletvalves a mixture is avoided even during charging. The provision ofseparate outlet valves in the two chambers has the advantage that burntgas is constantly expelled. Any reduction of the quality of the chargeby means of burnt gases is thus prevented;

I declare that what I claim is In an internal combustion engine, aWorking cylinder with inlet and outlet valves and a piston, a smallercylinder in alignment with and projecting from the end of thefirst-named cylinder and provided with inlet and outlet valves, a.conduit connecting the. last-named inlet valve with a source of richgas, and a small piston carried by the main piston and loosely fittingthe smaller cylinder.

In testimony whereof I atfix my signature.

FERDINAND PORSCHE.

